Looking at tendril cells under a microscope.
 

Hello,
I have several questions about using a microscope to see how cell
structure changes when a tendril bends in response to touch. It is
for a high school science fair project. The project involves growing
morning glories, and then inducing the tendrils to wrap around a
pencil. You then cut the end of the tendril, including the tip and a
full wrap. Next you cut a layer of cells from the outer edge and
another layer from the inner edge. The last part is to look at the cut
sections under a microscope to see how the cell structure has changed.
The hypothesis is that the cells will be longer on the outer edge,
which is what causes the tendril to bend.

Will I need a special dye to see the cells, or can I just look at them
under the scope as is? Do I need a coverslip? What magnification
would be best?
Thanks!

If you need to see changer in cell structure, you definitely need a dye. Although I can't guide you the whole process coz I'm still learning (I'm a biology student), all I can say is You have a very good idea for a science project.